Variable-Speed Pump Control for Adsorption Energy Savings

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Solution Overview

Problem

Variable-rate pumping in petroleum and petrochemical processes, particularly in simulated-moving-bed adsorption processes, results in significant energy inefficiencies due to substantial energy consumption by pumps circulating varying quantities of material across adsorbent chambers, leading to high energy losses and costs.

Innovation Solution

Implementing variable-speed driving means for pumps and utilizing a predictive load control algorithm to manage the flowrate of circulating streams through adsorbent chambers, replacing traditional control valves with variable-speed pumps and drivers, and adjusting pump speeds in conjunction with rotary valve indexing to maintain consistent pressure and optimize fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional control valves are used to manage variable flow rates in circulating streams, then flow control is achieved, but significant energy losses occur due to pressure drops

Engineering Contradiction:

Improveflow control capabilityVSAvoidenergy losses from pressure drops

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical control valves with variable-speed pumps driven by variable-speed motors. Instead of using valves to restrict flow and create pressure drops, the system uses pumps that can adjust their rotational speed to match the required flow rate, eliminating the energy-wasting pressure drops associated with valve control while maintaining flow control capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements dynamic control of pump speed based on the actual flow requirements of the circulating stream. The variable-speed motors allow the pumps to adjust their operating speed in real-time according to process conditions, transitioning from static, fixed-speed pump operation to dynamic, adaptive speed control that minimizes energy consumption while maintaining operational flexibility.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If pumps circulate varying quantities of material through adsorbent chambers, then process flexibility is achieved, but energy consumption increases significantly

Engineering Contradiction:

Improveprocess flexibilityVSAvoidpump energy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent applies variable-speed driving to the pumps, enabling them to dynamically adjust their rotational speed according to the varying flow requirements of the circulating stream. This dynamic speed adjustment allows the system to maintain process flexibility and adaptability while significantly reducing energy consumption compared to fixed-speed pumps that must operate at full capacity regardless of actual demand.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameter of the pumps from fixed speed to variable speed. By controlling the rotational speed of the pumps as a variable parameter rather than a fixed value, the system can optimize energy consumption at different operating conditions while maintaining the ability to circulate varying quantities of material through the adsorbent chambers as required by the process.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If fixed-speed pumps are used in simulated-moving-bed adsorption processes, then equipment simplicity is maintained, but energy inefficiency occurs during variable-rate pumping

Engineering Contradiction:

Improvepump system simplicityVSAvoidenergy inefficiency in variable-rate pumping

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent replaces simple fixed-speed pump motors with variable-speed motor drives. This substitution adds a control system component that enables speed variation, and while it increases device complexity slightly, it eliminates the severe energy inefficiencies associated with using fixed-speed pumps in variable-rate applications, achieving a net improvement in overall system efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces energy waste by minimizing pressure drops and related energy losses, achieving substantial energy savings and cost reductions in processes like para-xylene separation from mixed C8 aromatics, with potential savings of up to 46.3% of total pump energy usage.

Implementation Method 1

a solid adsorbent which preferentially retains the extract in order to separate the extract from the rest of the mixture

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

pumps circulating liquid from the bottom to the top of the bed of adsorbent

Methodology Applied

Scientific EffectPumping: Pump

Data Source

PatentUS9085499B2Energy efficiency in adsorptive separation

Publication Date: 2015.07.21 UOP LLC

AI summary

The present process comprises a means for energy savings in one or more process pumps by driving the one or more pumps with a variable-speed driving means. The invention is particularly useful in the separation of an adsorbed product from a mixture of components using simulated-moving-bed adsorption associated with a large circulating stream pumped with variable-speed driving means for conservation of energy relative to the known art. The improvement is particularly applicable to a process for the separation of para-xylene from mixed C8 aromatics.